Positioning apparatus



June 1, 1965 J. A. RODDER POSITIONING APPARATUS Filed Jan. 16, 1963 IN VEN TOR. 00004 P000150 United States Patent M 3,186,705 PfldiTTONlNG APPTUS Jerome A. Rudder, 775 Sunshine Drive, Los Altos, Calif. Filed ian. 16, 1963, Ser. No. 251,834 19 Claims. (Cl. 2696tl) This invention relates to apparatus for holding articles, samples, and the like in accurate but adjustable locations.

One of the important applications of this invention is the holding of liquid samples in a beam of light for optical analysis. Many times the amount of sample available for illumination is very small, and consequently must be placed in a correspondingly small container. In the optical analysis of such samples, it is imperative they be accurately and reproducibly disposed in carefully determined positions in a beam of light.

In a typical optical analytical instrument, four sample containers or cells are mounted on a carriage which can be moved across a narrow beam of light, thereby successively moving each of the four cells into the path of 7 light. The samples may be all unknowns, or one or more may be a standard known material. In any event, it is important that each sample be held in an accurately determined position in the beam of light. Previously avail-- able apparatus not only is deficient inaccuracy in positioning the samples, but it fails to provide any means for making slight adjustments in the final position of the sample to accommodate variation in samples, cells, tem'- peratures, etc.

This invention provides apparatus in which one or more sample cells, or any other object, can be accurately positioned with respect to a reference point, such as a Moreover,

also provided for moving the guide rod with respect to the frame to shift the location determined by the detent means. Preferably, the rod is threaded in the frame and is movable longitudinally.

The preferred embodiment of the invention includes.

a pair of guide rods, each threaded in the frame so that each is independently longitudinally adjustable with respect to the frame. Separate detent means are provided on each rod and the carriage. Thus, each rod is longi-. tudinally adjustable so that the position determined by its respective detent may be shifted. .A stop screw .is provided on the frame to engage the carriage and limit its longitudinal travel in one direction. Preferably, the stop screw is longitudinally adjustable. A positioning shaft is threaded through the carriage to project from it and engage the frame as the carriage is moved longitudinally in the other direction along the guide rods. The amount of projection of shaft from the carriage is adjustable by rotating the shaft with respect to the carriage, and thus provides an adjustable stop on the carriage to engage the frame.

To provide improved accuracy in holding the carriage in a fixed position on the guide rod, a special detent mechf aisanis ?atented June 1, 1965 anism is used. Briefly, the detent includes a body having a bore in which a detent pin is disposed to make a close sliding fit. A transverse cantilever spring is disposed in a transverse bore which intersects the first bore and is secured to the pin at one end and to the body at the other end. By this construction, a minimum amount of machining is necessary to make the detent mechanism, and the detent pin is provided with maximum longitudinal support in its bore for maximum accuracy.

These and other aspects of the invention will be more fully understood from the following detailed description and the accompanying drawings inwhich:

FIG. 1 is an elevation, partly broken away, of the presently preferred embodiment of the invention;

FIG. 2 is a plan view, partly broken away, of the ap tioned. For example, the particular frame shown in the drawing is well suited for mounting in the path of a beam of light used in aconventional spectrophotometer (not shown) in which samples are analyzed by shining a narrow beam of light through them.

A first horizontal guide rod 13 makes a close fit at its right (as viewed in PEG. 1) end in the left end of a stepped horizontal bore l4 at the lower end of the right postof the frame. The left end of the first guide rod makes a close fit in a horizontal bore 15 at the lower end of. the left post of theframe, and bears against a compression spring 16, which bears against a plug 17 secured in the left end of the bore 15. 'The right end of' the guide rod bears against an adjustable screw 18 threaded into the right end of bore 14 so the rod can easily be adjusted longitudinally with respect to the frame. An annular groove 19 in the first rod a short distance from the right post forms a portion of a first detent means which is adapted to lock a carriage Ell in a fixed position on the first guide rod. The. carriage includes a horizontal and rectangular platform 21 with right and left downwardly extending legs 22, 23, respectively. The first guide rod makes a close fit through collinear bores 24 and 25 in the right and left legs, respectively, of the carriage.

A second elongated horizontal guide rod 26 is laterally spaced from the first guide rod, and is secured through the a lower ends of the post exactly as described for the first guide rod. The second rod is identical with the first, except that the second rod has an annular detent groove 27 in its central portion rather than. adjacent one end. The second rod makes a loose fit through a pair of outwardly opening notches 23 and 29 in the right and left legs. of the carriage. The loose fit of rod 26 as compared to the close fitof rod 13 assures freedom of'movement for carriage 2t} alongthe rods without any possibility of binding which might be caused by a movement of the carriage which is not precisely longitudinally parallel with the guide rods. A middle leg 39 extends down from the carriage and contains a detent mechanismfil which 7 is shown in detail in FIG. 3. The middle leg also has an zontal bore 36 that crosses the vertical detent bore 34.

The other end of the spring is secured to the detent pin to urge the lower end of the pin to project downwardly into the notch 32 and engage the detent groove 27,

which has sloping sides 38 to facilitate retraction of the detent pin as the carriage is forced to move longitudinally- The right leg 22 of the carriage.

along the guide rods. has a detent mechanism identical with that shown in FIG. -3 to engage the annular groove 19, andtherefore is not described in detail.

An elongated, horizontal positioning. shaft 39 has a knob 40 on its right (as viewed in FIGS. 1 and 2) end, and extends from outside the right-end of the frame through a shaft bore 41 and the lower end of the right post, makes a loose fit through a bore 42 in the right leg of the carriage, and is threaded at its left end in a bore 43 in the left leg of the carriage.

A stop screw 44 is threaded through the lower end of the right post of the frame to provide a stop for the car-.

riage in the extreme right position. The stop screw can be adjusted longitudinally to vary the location at which the carriage comes to rest at the right end of its travel along the guide rods.

Four sample containers or' cells 45 '(shown only in phantom line in FIG. 1) are mounted on top of the carriage by any suitablev conventional means. The sample cell on the'right end of the carriage is placed 'in a beam of light (not shown) passing through the, center. of the frame in a direction perpendicularto the plane of FIG. 1 by pushing the positioning shaft to the left until the left end of the shaft strikes the inside face of the left post. The exact position of the carriage in this position is given a fine adjustment by rotating'the shaft with the knob 40. To. place the next cell in the path of the beam of light, the positioning shaft is pulled to the right until the detent'piu in the middle leg of the carriage engages the notch in the second guide; rod as shown in FIG. 1. The exact location determined by the detent arrangement is adjusted by rotating the guide rod to shift 'its position longitudinally. The next cell is placed in position by moving the positioning shaft to the right until the detent arrangement in the right leg of the carriage engages the groove 19 in the first guide rod. This exact positioning is given a fine adjustment by rotating the guide rod adjustment screw 18'to move it in the threaded sleeve in the lower end of the right post of the frame. The last cell is placed in the proper position by pulling the shaft to therighttuntil the right end ofthe carriage strikes the inner end of the stop screw 44,"which is adjusted longie tudinally to provide micro-positioning of the carriage.

Thus, the apparatus of this invention provides means for accurately locating a carriage in a plurality of fixed and reproducible positions which can be individually and finely adjusted.

I claim: a 1. Positioning apparatus comprising a frame, an elongated guide rod secured to the frame, a carriage mounted to slide along the guide rod, detent means for holding the carriageat a fixed location on the guide rod, and means means. 7

' 4 threaded bore, an elongated guide rod movably positioned in said bore and butted against an adjustment screw threaded in the bore in the frame, a carriage mounted to slide along the guide rod, detent means for holding the carriage at a fixed location on the guide rod, and means for rotating the guide rod adjustment screw with respect to the frame to shift the location determined by the detent means.

4. Positioning apparatus comprising a frame, a pair of laterally spaced elongated guide rods secured to the frame, a carriage mountedto slide along the guide rods, sep arate detent means on each rod and the carriage for holding the carriage at longitudinally spaced locations on the guide rod, and means for moving each guide rod with respect to the frame to shift the respective location determined by the detent means on each rod.

5. Positioning apparatus comprising a frame, a pair of laterally spaced elongated guide rods securedto theframe, a carriage mounted to slide along the guide rods, the carriage making a closer sliding fitalong one of the rods than along the other, detent means for holding the carriage at a fixed location on at least one of the guide rods, and means for moving said one guide rod with respect to the frame to shift the location determined by the detent 6. Positioning apparatus, comprising a' frame, an elongated guide rod secured-to the frame, a carriage mounted to slide along the guide rod, detent means for holding the carriage at a fixed location on the guide rod, means for moving the guide rod with respect to the frame to shift the location determined :by thedetent means, a stop mounted on the frame to limit the longitudinal travel of the carriage along the rod in one direction, and means for adjusting the position of the stop.

, 7. Positioning apparatus comprising a frame, an elongated guide rod securedto the frame, a carriage mounted to slide along the guide rod, detent means for holding the carriage at a fixed location on the guide rod, a positioning shaft secured to thecarriage, means forsliding the shaft "with respect to the. frame to move the carriage along the gated guide rod secured to the frame, a carriage mounted to slide along the guide rod, detent means for holding the carriage at a fixed location on the guide rod, means for moving the guide rod with respect to the frame to shift the-location determined by the detent means, and an elongated positioning shaft extending generally parallel to the for moving the guide rod with respect to the frame to 3. Positioning apparatus comprising a frame having a.

rod and threaded through the carriage so that one end of' the shaft forms an adjustable, stop on the carriage to engage the frame and limit longitudinal movement of the carriage along the rodin one direction. I

9. A slidable detent mechanism" comprising a housing having a first bore opening slidably surrounding a rod having an annular groove thereon, said housing having a bore transverse to said first bore opening and communicating therewith, a detent pin disposed in said transverse bore and projecting into said first bore, a cantilever spring fixed at one end to said housing and at its other end to said detent pin, said spring being normally loaded to urge said detent pin against said rod during sliding of said mechanism and to achieve longitudinal displacement of the pin into the annular groove for interrupting said sliding movement when the annular groove and the transverse bore are collinear.

10.-A slidable detent mechanism comprising a body having a first bore opening out of it and a second oversize'd bore passing through said body and in plane substantially parallel, with the plane of said first bore and surrounding a rod having an annular groove thereon, said body further having a transverse bore intersecting the first bore and opening into said second bore, a detent pin disposed in said transverse bore and projecting into said 7 References Cited by the Examiner second bore for bearing against said rod to achieve 21 UNITED STATES PATENTS close sliding fit for the rod in the second bore, and a 684 018 10/01 Wellman V transverse cantilever spring disposed in said first bore and 13625085 2/21 Womack X secured at one end to the detent pin and at its other end to 5 1 577 129 3 2 Knutson 2 75 one end of the first bore to achieve longitudinal displace- 2,864,279 12/58 Phife ment of the pin into the annular groove of the rod when FRANK SUSKO, Primary Examiner the detent mechanism is slid along the rod. ROBERT RIORDON, Examinen 

1. POSITIONING APPARATUS COMPRISING A FRAME, AN ELONGATED GUIDE ROD SECURED TO THE FRAME, A CARRIAGE MOUNTED TO SLIDE ALONG THE GUIDE ROD, DETENT MEANS FOR HOLDING THE CARRIAGE AT A FIXED LOCATION ON THE GUIDE ROD, AND MEANS FOR MOVING THE GUIDE ROD WITH RESPECT TO THE FRAME TO SHIFT THE LOCATION DETERMINED BY THE DETENT MEANS. 